Dual node multiray electrode catheter

ABSTRACT

This disclosure is directed to a catheter having a dual node multiray electrode assembly at the distal end of the catheter body. The dual node multiray electrode assembly includes a proximal multiray array with a plurality of spines connected at one end, each spine having at least one ablation electrode, and a distal node. The dual node multiray electrode assembly may have an expanded configuration and a collapsed configuration wherein the spines are arranged generally along a longitudinal axis of the catheter body. The distal node may be configured to be deployed within a vessel and the proximal multiray array may be configured to engage tissue forming an ostium of the vessel with the ablation electrodes. In some embodiments, the relative distance between the proximal multiray array and the distal node is adjustable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of commonly-assignedco-pending U.S. patent application Ser. No. 14/853,653, filed Sep. 14,2015, now U.S. Pat. No. 10,357,173, the entire disclosure of which isincorporated by reference.

FIELD OF THE PRESENT DISCLOSURE

This invention relates to electrophysiologic (EP) catheters, inparticular, EP catheters for mapping and/or ablation in the heart.

BACKGROUND

Electrophysiology catheters are commonly-used for mapping electricalactivity in the heart and/or for delivering ablative energy. Variouselectrode designs are known for different purposes. For example,catheters having basket-shaped electrode arrays are known and described,for example, in U.S. Pat. Nos. 5,772,590, 6,748,255 and 6,973,340, theentire disclosures of each of which are incorporated herein byreference.

Cardiac arrhythmia, such as atrial fibrillation, occurs when regions ofcardiac tissue abnormally conduct electric signals to adjacent tissue,thereby disrupting the normal cardiac cycle and causing asynchronousrhythm. Important sources of undesired signals are located in the tissueregion along the pulmonary veins of the left atrium. In this condition,after unwanted signals are generated in the pulmonary veins or conductedthrough the pulmonary veins from other sources, they are conducted intothe left atrium where they can initiate or continue arrhythmia.

Procedures for treating arrhythmia include surgically disrupting theorigin of the signals causing the arrhythmia, as well as disrupting theconducting pathway for such signals. More recently, it has been foundthat by mapping the electrical properties of the endocardium and theheart volume, and selectively ablating cardiac tissue by application ofenergy, it is sometimes possible to cease or modify the propagation ofunwanted electrical signals from one portion of the heart to another.The ablation process destroys the unwanted electrical pathways byformation of non-conducting lesions. An example of such an ablationprocedure is termed pulmonary vein isolation, and involves the ablationof tissue in the area adjacent the junction of the pulmonary veins andthe left atrium. The resulting lesion(s) may isolate irregularelectrical signals originating in the area from spreading through therest of the atrium and disrupting the patient's heart beat.

For these and other applications, conventional practice may involvepositioning an ablation catheter adjacent target regions to deliversufficient energy to form the non-conducting lesions in acircumferential path around a vessel such as a pulmonary vein.Accordingly, it would be desirable to provide a catheter and a techniquefor facilitating electrical isolation of a source of unwanted signalswithin such a vessel. Likewise, it would be desirable it reduce or avoidthe need to reposition a catheter while performing the ablationprocedure. As will be described in the following materials, thisdisclosure satisfies these and other needs.

SUMMARY

The present disclosure is directed to a catheter with an elongatedcatheter body having proximal and distal ends and a dual node multirayelectrode assembly at the distal end of the catheter body, wherein thedual node multiray electrode assembly comprises a proximal nodeincluding a multiray array with a plurality of spines connected at oneend, each spine having at least one ablation electrode, and a distalnode including an inflatable balloon, and wherein the dual node multirayelectrode assembly has an expanded configuration and a collapsedconfiguration wherein the spines of the proximal multiray array arearranged generally along a longitudinal axis of the catheter body andthe distal node conforms to the catheter body in the collapsedconfiguration.

In one aspect, the distal node may be configured to be deployed within avessel in the expanded configuration and wherein the proximal multirayarray may be configured to engage tissue of an ostium of the vessel withat least one of the ablation electrodes in the expanded configuration.

In one aspect, the elongated catheter body may have an inner tubularmember slidably disposed within a lumen of an outer tubular member andwherein the proximal multiray array may be secured to a distal end ofthe outer tubular member and the distal node is secured may be a distalend of the inner tubular member. Relative longitudinal movement of theinner tubular member and the outer tubular member may adjust a distancebetween the proximal multiray array and the distal node.

In one aspect, each spine of the proximal multiray array may have aplurality of independently controlled ablation electrodes.

In one aspect, the spines of the proximal multiray array may curveradially outward in the expanded configuration. The spines may curveproximally or distally.

This disclosure also includes a method for treatment. In one aspect, themethod may involve providing a catheter with an elongated catheter bodyhaving proximal and distal ends and a dual node multiray electrodeassembly at the distal end of the catheter body, wherein the dual nodemultiray electrode assembly comprises a proximal node including amultiray array with a plurality of spines connected at one end, eachspine having at least one ablation electrode, and a distal nodeincluding an expandable balloon, and wherein the dual node multirayelectrode assembly has an expanded configuration and a collapsedconfiguration wherein the spines of the proximal multiray array arearranged generally along a longitudinal axis of the catheter body andthe distal node conforms to the catheter body in the collapsedconfiguration, positioning the distal end of the catheter at a desiredregion of the heart, deploying the balloon within a vessel in theexpanded configuration to engage an inner diameter of the vessel, andpositioning the proximal multiray array to bring at least one ablationelectrode into contact with tissue forming an ostium of the vessel.

In one aspect, radio frequency energy may be delivered to the ablationelectrodes to form lesions. The lesions may be formed in acircumferential path around the ostium of the vessel.

In one aspect, a relative distance between the proximal multiray arrayand the distal node may be adjusted. Adjusting the relative distancebetween the proximal multiray array and the distal node may includeanchoring the distal node within the vessel and advancing the proximalmultiray array towards the distal node to bring the at least oneablation electrode into contact with tissue of the ostium.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become apparent from the followingand more particular description of the preferred embodiments of thedisclosure, as illustrated in the accompanying drawings, and in whichlike referenced characters generally refer to the same parts or elementsthroughout the views, and in which:

FIG. 1 is a top plan view of a catheter of the present invention, with adual node multiray electrode assembly in an expanded configurationhaving spine that curve proximally, according to one embodiment.

FIG. 2 is a schematic view of a dual node multiray electrode assemblyhaving an expanded configuration with spines that curve distally,according to one embodiment.

FIG. 3 is a schematic view of a dual node multiray electrode with aninflatable balloon distal node, according to one embodiment.

FIG. 4 is a schematic view of a dual node multiray electrode with astent distal node, according to one embodiment.

FIG. 5 is a schematic view of a dual node multiray electrode with abasket-shaped electrode assembly distal node, according to oneembodiment.

FIG. 6 is a schematic view of a dual node multiray electrode positionedwithin the left atrium, according to one embodiment.

FIG. 7 is a schematic illustration of an invasive medical procedureusing a dual node multiray electrode assembly, according to oneembodiment.

DETAILED DESCRIPTION

At the outset, it is to be understood that this disclosure is notlimited to particularly exemplified materials, architectures, routines,methods or structures as such may vary. Thus, although a number of suchoptions, similar or equivalent to those described herein, can be used inthe practice or embodiments of this disclosure, the preferred materialsand methods are described herein.

It is also to be understood that the terminology used herein is for thepurpose of describing particular embodiments of this disclosure only andis not intended to be limiting.

The detailed description set forth below in connection with the appendeddrawings is intended as a description of exemplary embodiments of thepresent disclosure and is not intended to represent the only exemplaryembodiments in which the present disclosure can be practiced. The term“exemplary” used throughout this description means “serving as anexample, instance, or illustration,” and should not necessarily beconstrued as preferred or advantageous over other exemplary embodiments.The detailed description includes specific details for the purpose ofproviding a thorough understanding of the exemplary embodiments of thespecification. It will be apparent to those skilled in the art that theexemplary embodiments of the specification may be practiced withoutthese specific details. In some instances, well known structures anddevices are shown in block diagram form in order to avoid obscuring thenovelty of the exemplary embodiments presented herein.

For purposes of convenience and clarity only, directional terms, such astop, bottom, left, right, up, down, over, above, below, beneath, rear,back, and front, may be used with respect to the accompanying drawings.These and similar directional terms should not be construed to limit thescope of the disclosure in any manner.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one having ordinaryskill in the art to which the disclosure pertains.

Finally, as used in this specification and the appended claims, thesingular forms “a, “an” and “the” include plural referents unless thecontent clearly dictates otherwise.

Certain types of electrical activity within a heart chamber are notcyclical. Examples include atrial fibrillation and other asynchronousconditions that may result from undesired signals originating in thepulmonary veins. As noted, RF energy may be delivered to selectedtreatment areas with a goal of isolating the source of irregularelectrical signals by blocking electrical conduction. Important clinicaltherapies for pulmonary vein isolation include RF ablation via focal ormultielectrode catheters.

Focal ablations using unipolar devices benefit from targeted delivery ofRF energy along with localized feedback of catheter placement, bothspatially and with respect to tissue engagement. However, focal ablationprocedures typically involve relative long procedure times as a resultof the physician needing to stitch a series of “quantized” RF ablationinto a continuous circumferential block which surrounds the ostium ofthe targeted vein. Additionally, the use of a focal unipolar electroderequires substantial physician skill levels augmented with peripheralnavigation systems in order to accurately and reliably position theelectrode sequentially along the desired circumferential path.

Correspondingly, the use of a multielectrode device seeks to capitalizeon the somewhat predictable anatomical structure of the pulmonary veinin order to place an array of unipolar electrodes in a fixedcircumferential path around the inner diameter of a targeted vein. RFenergy may then be delivered simultaneously to the electrode array,thereby theoretically reducing the time for therapeutic delivery bycreating the requisite ablations in parallel. In practice, it has beenobserved that it may also be difficult to properly orient the electrodearray with respect to the ostium of a pulmonary vein and to maintainsufficient engagement between the ablation electrodes and the tissue.Suboptimal tissue engagement results in ineffective energy delivery atsome electrode sites and necessitates additional device placements, orin some cases, lesion closure via unipolar ablations from a focal typedevice.

As will be described herein, this disclosure is directed to a catheterhaving a dual node multiray electrode assembly. The electrode assemblyfeatures a proximal node with multiple spines having a preshapedexpanded configuration that facilitates deployment in a desiredorientation with respect to a vessel, such as a pulmonary vein. Eachspine may carry one or more ablation electrodes. The preshaped expandedconfiguration may also help ensure sufficient contact between theablation electrodes and the target tissue to allow proper lesionformation.

The distal node is configured to be deployed within a vessel, such as apulmonary vein, during the ablation procedure. The distal node may alsohave multiple spines with a pre-shaped expanded configuration thatengages the inner diameter of the vessel to stabilize and orient theelectrode assembly, including the proximal node. In some embodiments,each spine of the distal node may carry one or more diagnosticelectrodes spaced along the spine to record signals during theprocedure.

The use of diagnostic electrodes on the spines of the distal node isadvantageous because after an ablation, these diagnostic electrodes canhelp the user (physician) determine if an effective lesion was created.The user can see if intra-cardiac signals arriving to the proximal nodeelectrodes are decoupled from signals on the distal node electrodes.Likewise, the user can see if signals arriving to the distal nodeelectrodes are decoupled from signals on the proximal node electrodes. Auser could also pace from the proximal node electrodes and verify thatthere is no capture on the distal node electrodes, or alternatively,pace from the distal node electrodes and verify there is no capture onthe proximal node electrodes. This would help the user confirm that aneffective lesion has been created because it blocks signals from bothdirections. Moreover, due to anatomical variations of the pulmonaryveins, multiple electrodes on the spines of the distal node would helpensure that at least one electrode along each spine is in contact withthe pulmonary vein. This too improves confirmation that an effectivelesion was created by seeing decoupled signals between the proximal anddistal node electrodes.

In other embodiments, the distal node may employ a different type ofexpanding structure, such as a balloon, a stent, a basket-shapedelectrode assembly or the like, again so that the expanded configurationengages the inner diameter of the vessel in which it deployed to helpstabilize the electrode assembly.

To help illustrate these and other aspects of this disclosure, anembodiment as shown in FIG. 1 features catheter 10, having a proximalend with a control handle 12 and a distal end with a dual node multirayelectrode assembly 14. Dual node multiray electrode assembly 14 mayinclude a proximal multiray array 16 and a distal multiray array 18,each having a plurality of spines 20. Each spine 20 of proximal multirayarray 16 may have one or more ablation electrodes 22, which may beconfigured as cup or ring electrodes depending on their position alongthe spine. Similarly, at least one spine 20 of distal multiray array 18may have one or more diagnostic electrodes 24, which also may beconfigured as cup or ring electrodes as warranted. In the depictedembodiment, each spine 20 of distal multiray array 18 may have one ormore diagnostic electrodes 24. To enable adjustment in the relativedistance between proximal multiray array 16 and distal multiray array18, proximal multiray array 16 may be secured to the distal end of anouter tubular member 26 that is slidably disposed over inner tubularmember 28. Control handle 12 may be secured to inner tubular member 28and an actuator 30 may be secured to the proximal end of outer tubularmember 26, so that by manipulating control handle 12 and actuator 30 toslide longitudinally relative to each other, an electrophysiologist maycontrol the distance between proximal multiray array 16 and distalmultiray array 18 at the distal end of catheter 10. In some embodiments,dual node multiray electrode assembly 14 may include one or more single-or multi-coil position sensors, such as sensor 32 located in distalmultiray array 18. As described below, such position sensors may be usedto help determine the position and/or orientation of dual node multirayelectrode assembly 14 within the patient. The relative position ofproximal multiray array 16 may be determined from the relationshipbetween actuator 30 and control handle 12 or proximal multiray array 16may also be equipped with a position sensor or sensors as desired.

Inner tubular member 28 and outer tubular members 26 may constitute thecatheter body and each may feature an elongated construction with asingle, axial or central lumen, but can optionally have multiple lumensif desired. In particular, outer tubular member 26 may have a centrallumen within which inner tubular member is coaxially disposed. Innertubular member 28 may also feature one or more lumens for any suitablepurpose, such as to deliver irrigation fluid, and to route cablingand/or leads associated with electrodes 22 and/or 24, position sensor32, other sensors or for any other suitable purpose.

The numbers of spines 20 forming proximal multiray array 16 and distalmultiray array 18 may be the same or different, and may be in the rangeof approximately 5 to 12 or any other suitable number. Spines 20 may beevenly or unevenly distributed radially. Further, each spine 20 mayinclude multiple electrodes 22 or 24. For ablation electrodes 22, eachelectrode per spine may be independently controlled as desired.Depending on the number of electrodes employed, they may be evenlydistributed along the spine or may be skewed proximally, centrally ordistally to facilitate analysis of the measured electrical signalsand/or ablation of tissue.

Inner tubular member 28 and outer tubular members 26 are flexible, i.e.,bendable, but substantially non-compressible along their lengths. Thetubular members may be of any suitable construction and made of anysuitable material. One construction comprises an outer wall made ofpolyurethane or PEBAX® (polyether block amide). The outer wall comprisesan imbedded braided mesh of stainless steel or the like to increasetorsional stiffness, so that rotation of a proximal end is translatedinto a corresponding rotation of the distal end, to facilitate guidingand positioning of dual node multiray electrode assembly 14. The outerdiameter of outer tubular member 26 is not critical, but generallyshould be as small as possible and may be no more than about 10 frenchdepending on the desired application. Likewise the thicknesses of theouter walls of the tubular members is not critical, but may be thinenough so that interior lumens can accommodate a puller wire, leadwires, sensor cables and any other wires, cables or tubes. If desired,the inner surface of one or both outer walls may be lined with astiffening tube (not shown) to provide improved torsional stability. Anexample of a catheter body construction suitable for use in connectionwith the present invention is described and depicted in U.S. Pat. No.6,064,905, the entire disclosure of which is incorporated herein byreference.

In one aspect, spines 20 may include a material, such as a shape memorymaterial as described below, that facilitates assuming an expandedarrangement to bring electrodes 22 of proximal multiray array 16 intocontact or closer proximity with tissue forming the ostium of a vesseland to cause distal multiray array 18 to engage the inner diameter ofthe vessel to stabilize dual node multiray electrode assembly 14.Notably, as shown in FIG. 1, in one embodiment spines 20 of proximalmultiray array 16 and distal multiray array 18 may have a preshapedconfiguration in which they form an arc curving in the proximaldirection. As will be appreciated, the resiliency associated with thepreshaped configurations may facilitate bringing electrodes 22 and/or 24into contact with the surrounding tissue.

An exemplary construction of spines 20 may include a flexible wire orother structural support strut with a non-conductive covering on whichone or more of the electrodes 22 and/or 24 are mounted. In anembodiment, the flexible wires may be formed from a shape memorymaterial to facilitate the transition between expanded and collapsedarrangements and the non-conductive coverings may each comprise abiocompatible plastic tubing, such as polyurethane or polyimide tubing.For example, nickel-titanium alloys known as nitinol may be used. Atbody temperature, nitinol wire is flexible and elastic and, like mostmetals, nitinol wires deform when subjected to minimal force and returnto their shape in the absence of that force.

Nitinol belongs to a class of materials called Shaped Memory Alloys(SMA) that have interesting mechanical properties beyond flexibility andelasticity, including shape memory and superelasticity which allownitinol to have a “memorized shape” that is dependent on its temperaturephases. The austenite phase is nitinol's stronger, higher-temperaturephase, with a simple cubic crystalline structure. Superelastic behavioroccurs in this phase (over a 50°-60° C. temperature spread).Correspondingly, the martensite phase is a relatively weaker,lower-temperature phase with a twinned crystalline structure. When anitinol material is in the martensite phase, it is relatively easilydeformed and will remain deformed. However, when heated above itsaustenite transition temperature, the nitinol material will return toits pre-deformed shape, producing the “shape memory” effect. Thetemperature at which nitinol starts to transform to austenite uponheating is referred to as the “As” temperature. The temperature at whichnitinol has finished transforming to austenite upon heating is referredto as the “Af” temperature.

Accordingly, the dual node multiray electrode assembly 14 may have athree dimensional shape that can be easily collapsed to be fed into aguiding sheath and then readily returned to its expanded shape memoryconfiguration upon delivery to the desired region of the patient uponremoval of the guiding sheath. Alternatively, in some embodiments spines20 can be designed without the internal flexible wire if a sufficientlyrigid nonconductive material is used for the non-conductive covering topermit radial expansion of the dual node multiray electrode assembly 14,so long as the spine has an outer surface that is non-conductive over atleast a part of its surface for mounting of electrodes.

Other configurations of spines 20 may be employed, such as shown in FIG.2 in which the spines curve in the distal direction. In this embodiment,proximal multiray array 16 employs spines 20 that have multiple ablationelectrodes 22. Alternatively, the spines 20 of proximal multiray array16 and distal multiray array 18 may curve in either combination ofopposing directions. Regardless of the orientation of their curvature,spines 20 may be sized appropriately depending on the patient's anatomy.For example, spines 20 of proximal multiray array 16 may have a lengthand/or curvature configured to engage tissue forming the ostium of thevessel, while spines 20 of distal multiray array 18 may have a lengthand/or curvature adapted to form an expanded configuration that engagesthe inner diameter of the vessel. In some embodiments, the outerdiameter assumed by the expanded configuration of distal multiray array18 may be relatively smaller than the outer diameter assumed by proximalmultiray array 16.

As indicated above, this disclosure also includes embodiments in whichdual node multiray electrode assembly 14 employs a proximal multirayarray 16 similar to that described above but distal multiray array 18may be replaced by a different expandable distal node.

For example, FIG. 3 schematically illustrates an embodiment in which thedistal node is implemented using inflatable balloon 34. Balloon 34 mayemploy any suitable construction, such as those associated withangioplasty procedures or stent deployment. In its unexpanded, collapsedconfiguration, balloon 34 may conform closely to the outer diameter ofinner tubular member 28. Once positioned at a desired location within apatient's vessel, balloon 34 may be inflated, such as by the use of asuitable inflation fluid, until it assumes an expanded configurationthat engages the inner diameter of the vessel to help stabilize dualnode multiray electrode assembly 14.

In another example, FIG. 4 schematically illustrates an embodiment inwhich the distal node of dual node multiray electrode assembly 14 isimplemented using stent 36, or other similar expandable intraluminaldevice. Stent 36 may have an unexpanded, collapsed configuration thatconforms closely to the outer diameter of inner tubular member 28.Likewise, stent 36 may be expanded using any technique as known to thoseof skill in the art once positioned at a desired location within apatient's vessel. In its expanded configuration, stent 36 may engage theinner diameter of the vessel thereby stabilizing dual node multirayelectrode assembly 14.

Yet another example is schematically depicted in FIG. 5. In thisembodiment, the distal node of dual node multiray electrode assembly 14is configured as a basket-shaped electrode assembly 38. Basket assembly38 has a plurality of spines 40 connected at their proximal and distalends. Basket-shaped electrode assembly 38 has an expanded arrangementwherein spines 40 bow radially outwardly and a collapsed arrangementwherein spines 40 are arranged generally along the axis of the catheterbody. In some embodiments, the distance between the proximal and distalends of basket-shaped electrode assembly 38 may be shortened, such as bymoving puller wire 42 proximally, causing spines 40 to bow outwards intothe expanded configuration.

Alternatively, the construction of spines 40 may be similar to that ofspines 20, for example with respect to the use of shape memory materialsthat may cause basket-shaped electrode assembly 38 to assume itsexpanded configuration when unconstrained, such as by being advanced outof inner tubular member 28. As desired, spines 40 may also carry one ormore diagnostic electrodes 44 to measure electrical signals from withinthe vessel when basket-shaped electrode assembly 38 is deployed. Whenbasket-shaped electrode assembly 38 assumes its expanded configuration,spines 40 may engage the inner diameter of the vessel therebystabilizing dual node multiray electrode assembly 14.

In one aspect, an electrophysiologist may introduce a guiding sheath,guide wire and dilator into the patient, as is generally known in theart. Examples of suitable guiding sheaths for use in connection with theinventive catheter are the PREFACE™ Braided Guiding Sheath (commerciallyavailable from Biosense Webster, Inc., Diamond Bar, Calif.) and theDiRex™ Guiding Sheath (commercially available from BARD, Murray Hill,N.J.). The guide wire is inserted, the dilator is removed, and thecatheter is introduced through the guiding sheath whereby the guide wirelumen in the expander permits the catheter to pass over the guide wire.In one exemplary procedure as depicted in FIG. 6, catheter 10, disposedwithin guiding sheath 46 is first introduced to the right atrium (RA)via the inferior vena cava (IVC), where it passes through the septum (S)in order to reach the left atrium (LA).

As will be appreciated, guiding sheath 46 covers the spines 20 of thedual node multiray electrode assembly 14 in a collapsed position so thatthe entire catheter can be passed through the patient's vasculature tothe desired location. Once the distal end of the catheter reaches thedesired location, e.g., the left atrium adjacent a pulmonary vein,guiding sheath is withdrawn to expose the dual node multiray electrodeassembly 14. Once the guiding sheath is withdrawn, spines 20 flexoutwardly and assume their expanded configuration, such that distalmultiray array 18 may engage the inner diameter of the vessel (shown inphantom) and proximal multiray array 16 to bring one or more ablationelectrodes 22 into contact with tissue at desired regions.

In one aspect, multiple electrodes 22 may be in contact in acircumferential path around an ostium of a vessel, e.g., a pulmonaryvein. In another aspect, embodiments may allow adjustment of relativedistance between the proximal node and the distal node, for example byusing the techniques discussed above or others. Correspondingly,manipulation of actuator 30 and control handle 12 provides control overthe relative position of proximal multiray array 16 and distal multirayarray 18 through inner tubular member 28 and outer tubular member 26.

As will be appreciated, a procedure employing a dual node multirayelectrode assembly with the techniques of this disclosure allow anydesired sequence of operations to be performed, including, but notlimited to: expanding or allowing to expand either or both the proximaland the distal node; adjusting relative positioning between the proximaland distal nodes; recording electrical signals; and delivering energyfor ablation. As an illustration, one non-limiting aspect may involvedeploying the distal node within a vessel to serve as an anchor,adjusting the relative longitudinal position of the proximal node tofacilitate bringing one or more electrodes into a desired degree ofcontact with tissue on a circumferential path around the ostium of thevessel. Correspondingly, RF energy may be delivered to the ablationelectrodes to ablate tissue in a circumferential path around the innervessel wall. Depending upon the number of spines 20 and the numberelectrodes being employed, a substantially complete circumferentiallesion may be formed simultaneously in some embodiments.

In other embodiments, catheter 10 may be rotated after forming a firstset of lesions, so that electrodes 20 come into contact with new areasof tissue along the circumferential path and the delivery of ablationenergy may then be repeated. The sequence of rotation and delivery ofenergy may be repeated as warranted. Formation of a substantiallycomplete lesion around the circumference of the vessel may electricallyisolate the source of abnormal signals as described above.

To help illustrate use of dual node multiray electrode assembly 14, FIG.7 is a schematic depiction of an invasive medical procedure, accordingto an embodiment of the present invention. Catheter 10, with the dualnode multiray electrode assembly 14 (not shown in this view) at thedistal end may have a connector 60 at the proximal end for coupling theleads of the electrodes and sensors (not shown in this view) to aconsole 62 for recording and analyzing the signals they detect as wellas for supplying ablating energy. An electrophysiologist 64 may insertthe catheter 10 into a patient 66 in order to acquire electropotentialsignals from the heart 68 of the patient, such as via electrodes 24 ofdistal multiray array 18. The electrophysiologist 64 uses the controlhandle 12 attached to the catheter in order to perform the insertion.

Console 62 may include a processing unit 70 which analyzes the receivedsignals, and which may present results of the analysis on a display 72attached to the console. The results are typically in the form of a map,numerical displays, and/or graphs derived from the signals. Processingunit 70 may also control the delivery of energy to electrodes 20 ofproximal multiray array 16 for creating one or more lesions. Theelectrophysiologist 64 may perform the operations described above tocreate a substantially complete circumferential lesion.

Further, the processing unit 70 may also receive signals from positionsensors, such as sensor 32 (not shown in this view). As noted, thesensor(s) may each comprise a magnetic-field-responsive coil or aplurality of such coils. Using a plurality of coils enablessix-dimensional position and orientation coordinates to be determined.The sensors may therefore generate electrical position signals inresponse to the magnetic fields from external coils, thereby enablingprocessor 70 to determine the position, (e.g., the location andorientation) of the distal end of catheter 10 within the heart cavity.The electrophysiologist may then view the position of the dual nodemultiray electrode assembly 14 on an image the patient's heart on thedisplay 72. By way of example, this method of position sensing may beimplemented using the CARTO™ system, produced by Biosense Webster Inc.(Diamond Bar, Calif.) and is described in detail in U.S. Pat. Nos.5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, inPCT Patent Publication WO 96/05768, and in U.S. Patent ApplicationPublications 2002/0065455 A1, 2003/0120150 A1 and 2004/0068178 A1, whosedisclosures are all incorporated herein by reference. As will beappreciated, other location sensing techniques may also be employed. Inone aspect, the coordinates of the distal sensor relative to theproximal sensor may be determined and, with other known informationpertaining to the configuration of dual node multiray electrode assembly14, used to find the positions of each of the electrodes 22 and/or 24.

The preceding description has been presented with reference to presentlydisclosed embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale. Accordingly, the foregoingdescription should not be read as pertaining only to the precisestructures described and illustrated in the accompanying drawings, butrather should be read consistent with and as support to the followingclaims which are to have their fullest and fair scope.

What is claimed is:
 1. A catheter comprising an elongated catheter body having proximal and distal ends and a dual node multiray electrode assembly at the distal end of the catheter body, wherein the dual node multiray electrode assembly comprises a proximal node including a multiray array with a plurality of spines connected only at one end, each spine having at least one ablation electrode and a distal node including an inflatable balloon, and wherein the dual node multiray electrode assembly has an expanded configuration and a collapsed configuration wherein the spines of the proximal multiray array are arranged generally along a longitudinal axis of the catheter body and the distal node conforms to the catheter body in the collapsed configuration, the elongated catheter body comprising an inner tubular member slidably disposed within a lumen of an outer tubular member, a proximal end of the inner tubular member being secured to a control handle, the proximal node multiray array being secured to a distal end of the outer tubular member and the distal node being secured to a distal end of the inner tubular member.
 2. The catheter of claim 1, wherein the distal node is configured to be deployed within a vessel in the expanded configuration and wherein the proximal multiray array is configured to engage tissue of an ostium of the vessel with the at least one ablation electrode in the expanded configuration.
 3. The catheter of claim 1, wherein relative longitudinal movement of the inner tubular member and the outer tubular member adjusts a distance between the proximal multiray array and the distal node.
 4. The catheter of claim 1, wherein each spine of the proximal multiray array comprises a plurality of independently controlled ablation electrodes.
 5. The catheter of claim 1, wherein the spines of the proximal multiray array curve radially outward in the expanded configuration.
 6. The catheter of claim 5, wherein the spines of the proximal multiray array curve proximally.
 7. The catheter of claim 5, wherein the spines of the proximal multiray array curve distally.
 8. A method for treatment comprising: providing a catheter with an elongated catheter body having proximal and distal ends and a dual node multiray electrode assembly at the distal end of the catheter body, wherein the dual node multiray electrode assembly comprises a proximal node including a multiray array with a plurality of spines connected only at one end, each spine having at least one ablation electrode and a distal node including an expandable balloon, and wherein the dual node multiray electrode assembly has an expanded configuration and a collapsed configuration wherein the spines of the proximal multiray array are arranged generally along a longitudinal axis of the catheter body and the distal node conforms to the catheter body in the collapsed configuration, the elongated catheter body comprising an inner tubular member slidably disposed within a lumen of an outer tubular member, a proximal end of the inner tubular member being secured to a control handle, the proximal node multiray array being secured to a distal end of the outer tubular member and the distal node being secured to a distal end of the inner tubular member; positioning the distal end of the catheter at a desired region of the heart; deploying the balloon within a vessel in the expanded configuration to engage an inner diameter of the vessel; and positioning the proximal multiray array to bring at least one ablation electrode into contact with tissue forming an ostium of the vessel.
 9. The method of claim 8, further comprising delivering radio frequency energy to the at least one ablation electrode to form a substantially complete circumferential lesion.
 10. The method of claim 8, further comprising adjusting a relative distance between the proximal multiray array and the distal node.
 11. The method of claim 10, wherein adjusting the relative distance between the proximal multiray array and the distal node comprises anchoring the distal node within the vessel and advancing the proximal multiray array towards the distal node to bring the at least one ablation electrode into contact with tissue of the ostium. 